Due to actualization of environmental problems in recent years, hybrid cars and electric vehicles have spread. Then, as an air conditioner which is applicable to such a vehicle, there has been developed an air conditioner including a compressor to compress and discharge a refrigerant, a radiator disposed on the side of a vehicle interior to let the refrigerant radiate heat, a heat absorber disposed on the vehicle interior side to let the refrigerant absorb heat, and an outdoor heat exchanger disposed outside the vehicle interior to let the refrigerant radiate heat or absorb heat, and there are changeable a heating mode to let the refrigerant discharged from the compressor radiate heat in the radiator and let the refrigerant from which the heat has been radiated in this radiator absorb heat in the outdoor heat exchanger, a dehumidifying and heating mode to let the refrigerant discharged from the compressor radiate heat in the radiator and let the refrigerant from which the heat has been radiated in the radiator absorb heat in the heat absorber and the outdoor heat exchanger, a dehumidifying and cooling mode to let the refrigerant discharged from the compressor radiate heat in the radiator and the outdoor heat exchanger and let the refrigerant absorb heat in the heat absorber, and a cooling mode to let the refrigerant discharged from the compressor radiate heat in the outdoor heat exchanger and let the refrigerant absorb heat in the heat absorber (e.g., see Patent Document 1).
In this case, an outdoor expansion valve is disposed in an inlet of the outdoor heat exchanger, and an indoor expansion valve is disposed in an inlet of the heat absorber. Furthermore, a bypass circuit is disposed in parallel with a series circuit of the outdoor expansion valve and the outdoor heat exchanger. Then, in the above-mentioned dehumidifying and heating mode, the refrigerant flowing through the radiator is distributed, a part of the refrigerant flows from the bypass circuit through the indoor expansion valve in which the refrigerant is decompressed, and then flows into the heat absorber to absorb heat. Furthermore, the residual refrigerant flows through the outdoor expansion valve in which the refrigerant is decompressed, and then flow into the outdoor heat exchanger to absorb heat.
Additionally, in such a dehumidifying and heating mode, an operation of the compressor is controlled on the basis of a radiator pressure to control a heating capability by the radiator, and the outdoor expansion valve is controlled on the basis of a temperature of the heat absorber to control a dehumidifying capability (a cooling capability) by the heat absorber. Specifically, when the temperature of the heat absorber is lower than a target heat absorber temperature, a valve position of the outdoor expansion valve is expanded to decrease an amount of the refrigerant to flow from the bypass circuit to the heat absorber, and conversely, when the temperature of the heat absorber is higher, the valve position of the outdoor expansion valve is reduced to increase an amount of the refrigerant to flow into the heat absorber from the bypass circuit through the indoor expansion valve.